Shepherd was thrown out of Westminster Seminary for his unbiblical view on soteriology in 1981, but not without leaving his mark in the seminary's faculty, which remains a problem to this day.
This book contains some very simple words, combined in a way to form sentenses and paragraphs that make no sense. So it is hard for those who lack the ability to discern the subtleties of theological language -- let alone Shepherd's confused language -- to really understand what he is saying, and to realize how unbiblical his view is.
For a short critique, I suggest that you search the Internet for John Robbins' review on this book, entitled, "False Shepherd". I think he rightly calls Shepherd's view "Neo-legalism".
Coming out of a dispensationalist background, and not really knowing what Covenant Theology was about, I obtained this book with the hope of better understanding what has often been described to me as the core of Reformed theology. Instead, this work left me increasingly perplexed, as it seems to pour tension on other Reformed doctrines I have long since accepted (the doctrines of grace, justification by faith alone).
The first thing I found baffling is how the book attempts to address evangelism and "view election from the perspective of the covenant." The author does well to point out that the five points are not the exhaustive description of Calvinism, and that the believer has no business in trying to decipher who is elect and who is reprobate. But it is troubling that though he explicitly denies the Arminian position, his description of election sounds exceedingly corporate and conditional in character. Isn't that exactly what the Arminians affirm and the Calvinists deny?
The second and third points of confusion I found only after re-reading the book (since I didn't understand it the first time around), but trying to digest them, I find them more troubling than the first. The book says, concerning Jesus Christ himself, "His was a living, active, and obedient faith that took him all the way to the cross. This faith was credited to him as righteousness." Huh? Doesn't this just bring Jesus down to the our level, himself needing faith to be saved? Isn't this sort of teaching more at home with modernist innovation than with the historic Reformed faith? Isn't Christ the example to us in all things but faith? Rather, isn't he the object of faith? And isn't his righteousness intrinsic rather than imputed?
Third, and directly related to the second is the impression of how the sinner is justified. "Just as Jesus was faithful..., so his followers must be faithful in order to inherit the blessing." It is good that the author insists that a Christian has commandments to live by. But this, like many other statements in the book, muddies the waters. Regardless of what the author is trying to teach, it sounds very much like works. It is frustrating that no clear attempt is made to explain the obedient Christian life in relation to justification by faith alone.
I have since learned more of Reformed theology, and can conclude that this book is not a good introduction to the historic protestant faith. Indeed, through the fuzzy language, it almost sounds like the author repudiates the historic teaching that Christ satisfies the covenant conditions for us.
I am somewhat perplexed by the number of clearly Reformed reviewers giving such high marks for the book. I thought that it would be useful that this review be from my reaction as someone new to the systematic. Many of the statements made in the book I would not disagree with if taken alone, and many others I would heartily endorse. But as a unit, the book left me bewildered. Tensions are created rather than resolved, and poor neophytes (like me) are left more confused as to how the Covenant illuminates anything.